Alpha interferon produces sustained suppression of hepatitis B virus (HBV) replication in 30-40% of patients with chronic hepatitis B, but is ineffective in hepatitis B carriers. An important mechanism for clearance of HBV is through cytotoxic T cell (CTL) mediated lysis of infected hepatocytes. The target antigen has been identified to be hepatitis B core antigen (HBcAG). Recent studies showed that patients with chronic HBV infection have impaired CTL response to HBcAg. Cy1899 is a vaccine designed to augment an HBV specific CTL response. The HLA haplotype targeted by CY 1899 is HLA A2.1. HLA A2.1 is highly represented within different ethnic populations. The objectives of the study are to assess the safety and efficacy of CY 1899 in 1) patients with chronic hepatitis, and 2) hepatitis B carriers.